I've done experiments with resin casting out of RP masters, it's been a mixed bag so far.
1) You have to design the interior of the RP print smooth - really smooth - no undercuts, edges, etc. and other misc, hangups.
2) Whether your realize it or not - the RP prints are porous. They retain air. When you do the molds, they will outgas that air into the molding media (rubber or whatever). You need to seal/prime them in some manner to at least minimize it or you will have small bubbles everywhere on the molds.
3) Priming and sealing 'may' cause the master to both shrink and/or warp, depending on the material. I've proved it dimensionally.
4) Depending on what you're casting material is, you may have a shrinkage factor that needs to be addressed in the size ratio of the original print.
5) CR600 at least has a minimum wall thickness of about .020; you may get lucky but don't count on it of anything less than that.
6) FUD, anyway, is just incredibly brittle for a master and getting the molds off the master without damaging anything is always a challenge.
Despite all that, I've managed to do it, but it's a lot harder than I imagined. I've been used to scratchbuilding my masters out of wood, styrene, and metal and have literally made thousands of resin parts. I've made multi-part, rather complicated molds with all manner of inserts and using injection molded resin. This is still an adventure, and I've been casting now for 11 years.